作者：Ms.lin 链接：https://www.nowcoder.com/discuss/177870 来源：牛客网 逃生问题： 思路：根结点左右子树的最大结点数。本地测试通过，提交不通过，不知道哪错了，大佬们帮忙看看 import collections import sys n = int(input()) edges = [] while True:     a = []     s = input()     if s != "":         for x in s.split():             a.append(int(x))         edges.append(a)     else:         break graph = collections.defaultdict(set) for u, v in edges:     graph[u].add(v)     graph[v].add(u) def dfs(graph, node, visited):     count = 1     visited[node] = True     for child in graph[node]:         if not visited[child]:             count += dfs(graph, child, visited)     return count res = 0 visited = [False] * (n + 1) visited[1] = True for child in graph[1]:     nodeNums = dfs(graph, child, visited)     if res < nodeNums:         res = nodeNums sys.stdout.write(str(res)+"\n")